The present invention relates computer games and simulations, and more particularly to computer games and simulations using virtual reality. Even more particularly, the present invention relates to a method and apparatus for immersion of a user into virtual reality allowing natural human locomotion.
Virtual reality is a computer-generated reality that creates an illusion in a user that the user is in an artificially created world (virtual world). Virtual reality may stimulate naturally occurring senses such as sight, sound, touch, and movement. Actions of the user are translated by the computer into inputs that effect the virtual environment in which the user is in.
A major limitation in virtual reality systems is an inability for the system to allow natural human locomotion. Navigation is typically experienced as a disembodied center of consciousness directed by pointing, other gestures or by manipulation of a joystick, trackball, mouse, or similar device. The user, through the use of a head mounted display, is provided sensory information that the user is moving, but the user is located in a virtual reality pod and does not physically move. Disadvantageously, this causes discomfort and nausea in some users.
Other virtual reality systems comprise a treadmill that is connected to a computer system. This treadmill approach is very similar to the virtual reality pods except that the user is allowed uni-directional movement only. The user can walk forward and the virtual reality will respond accordingly; however, the user is unable to move backwards or side to side. Again, such a system does not allow for natural human locomotion and causes disorientation and potentially nausea in some users.
Still other approaches, such as shown in U.S. Pat. No. 5,562,572 (Carmein), hereinafter referred to as the '572 patent, use a treadmill that is able to move in both forward and reverse directions, as well as move from left to right. The user walks in a desired direction while sensors are positioned to detect which direction the user has walked. These sensors respond to signals transmitted from devices attached to the user's hands, waist, etc. The treadmill is then moved in the appropriate directions to continually bring the user back to the center of the treadmill. Motors are used that move the treadmill forward or backwards and left or right. Thus, the treadmill system senses movement and then reacts by moving the treadmill in such a manner to reposition the user in the center of the treadmill. Disadvantageously, expensive motors are needed, and more importantly, the system must physically move the user resulting in a potentially "jerky" motion as the user is repositioned in the center of the treadmill. If the user moves too quickly, e.g. beyond the pace of a walk, the system may not react in time and the user may actually walk off of the treadmill or the system may attempt to quickly move the user back to the center of the treadmill and "jerk" the user. This motion again may cause disorientation and nausea in some users. Furthermore, if the user trips or loses his or her balance, the user is not prevented from falling. Falling and loss of balance can occur is such systems since the user can not actually "see" the physical treadmill, only the virtual world presented. Thus, if the user experiences loss of balance, the user has difficult time recovering balance and may fall.
Yet another prior art approach, such as shown in U.S. Pat. No. 5,846,134 (Latypov), hereinafter referred to as the '134 patent, is for a user to be immersed inside of a large hollow sphere, for example 20 to 30 feet in diameter. The user is able to move in any direction; however, when the user begins to move from the center of the inside of the sphere, the user is essentially moving uphill, i.e. up the inside of the sphere. When the user reaches a certain point "up" the inside curvature of the sphere, the force of gravity or the use of a motor forces the sphere to rotate so that the user is again near the very bottom curve of the sphere. If the user moves too quickly in any direction, the sphere may not move fast enough to keep up and the user will have to stop or slow down so that the sphere will rotate enough to level the walking surface. Motors can be used to assist in turning the sphere; however, the motors must be precisely synchronized with the movement of the user inside in order to turn on and off depending on the velocity and direction of the user. It is difficult to start and stop the movement of the sphere using the motors especially if the user makes quick movements or changes velocity or direction. Additionally, in such a system, the user is not prevented from falling resulting from tripping or loss of balance as the user is walking "up" the inside of the sphere. Loss of balance is a problematic since the user wears a head mounted display and actually can't see the moving curved interior surface of the sphere. Disadvantageously, such a system requires expensive motors and sensing equipment and the processing demands are increased in order to translate the movement of the user into the virtual world. Disadvantageously, such a system would also require tremendous physical space to contain the large hollow sphere that may be up 20 to 30 feet in diameter, and the necessary supports and motors that are needed to support and turn the large hollow sphere.
Furthermore, in the described prior art systems, when a user encounters a barrier, e.g. a wall, within the virtual world provided, the user can simply "walk" right through barrier and the user does "feel" the barrier. Thus, conventional virtual reality equipment does not accurately simulate barriers.